1. Field of the Invention
The present invention relates to an image pickup device and an image pickup system.
2. Description of the Related Art
Examples of an image pickup device used in an electronic video camera or an electronic still camera include an MOS sensor or an X-Y address sensor. The X-Y address sensor obtains a signal from a pixel located at a specific position by specifying its address. With this feature, the X-Y address sensor realizes an “all pixel reading mode” in which signals of all pixels are obtained and a “reduced reading mode” in which (pixels in) some rows and columns are skipped and signals are obtained from other pixels.
In Japanese Patent Laid-Open No. 2008-288903, first storage means which stores an address on which shutter scanning is to be performed and a second storage means which stores an address on which reading scanning is to be performed are provided so as to perform a complicated shutter operation in the “reduced reading mode”, for example. Furthermore, Japanese Patent Laid-Open No. 2008-288903 also discloses a pixel sharing technique of sharing a floating diffusion which temporarily holds charge stored in pixels and which is a part of the transistors included in the pixels by a plurality of pixels, and also, a circuit for selecting a pixel in the technique.
However, if the circuit disclosed in Japanese Patent Laid-Open No. 2008-288903 is used in an image sensor which employs the pixel sharing technique, selection of a pixel may not be properly performed, and accordingly, an invalid operation may be performed.
Therefore, a need exists for an image pickup device, an image pickup system, and a method for driving the image pickup device which prevents an invalid operation from being performed even when the pixel sharing technique is employed.